1. Field of the Invention
The present invention generally relates to turbidity sensors. The present invention more particularly relates to a turbidity sensor with a tube through which the sensed media/liquid flows and which utilizes light for sensing the turbidity; and which may further contain conductivity sensors or the like for the sensed media.
2. Description of the Prior Art
Turbidity sensors utilizing light to sense the amount of particulates in a solution are known in the art. Reference may be had to U.S. Pat. No. 5,446,531 to Boyer et al. for background discussion of the related art as it might particularly apply to a fluid condition sensor which is placed in, or surrounded by, the liquid or media to be sensed.
Reference may also be had to U.S. Pat. No. 5,291,626 to Molnar et al. for discussion of a turbidity sensor of the visible light, or optical, variety in which the liquid to be sensed flows through a clear tube surrounded by the optical sensing components.
As seen in FIG. 1, a visible light flowthrough turbidity sensor, as currently known, utilizes a casing having first and second halves 11 and 13, respectively, which are opaque and which totally surround a quartz glass media tube 15 which is inserted through an opaque tube 17 contained on a PCB assembly 19 which contains the optical and electronic components required for the output of a turbidity signal. O-rings 21 and 23 are used at each end of the quartz glass media tube 15 to prevent ambient light from leaking into, and the sensed media from leaking out of the media tube.
However, this known arrangement, as seen in FIG. 1, has several disadvantages. First, related to the quartz glass media tube, the glass is expensive, brittle, and is subject to wide dimensional variations among different tubes due to inherent manufacturing tolerances. Therefore, the O-rings are made oversized so that they may account for the size variations within one or several runs of glass tube manufacture. Expense and breakability of the glass are obvious shortcomings in a manufacturing environment. Further, it is very difficult to insert additional probes through the glass wall of the tube in order to contact the media physically. Such probes as temperature or conductivity probes are therefore not easily integrated into this package. Further, anywhere there is an O-ring there is a potential failure point.
It is therefore an object of the present invention to provide a turbidity sensor which overcomes the cited difficulties of the known art and provides for a lower cost turbidity sensor package with additional design freedom for multiple sensing apparatus and which has a lower cost and fewer parts than the known visible light flowthrough turbidity sensor packages.